When political crises erupt in Ukraine, the fault line traditionally runs along the twisting Dnieper River which divides the Europe-oriented western half from the pro-Russian industrial east.

But the current crisis, prompted by President Viktor Yanukovych's decision to hold off on signing a monumental and long-negotiated Association Agreement with the European Union, seems to be showing that that division is not so cut-and-dried as it has been in the past. The politically weakened Yanukovych cannot count on the kind of mass support -- and oligarchic financial backing -- from his home base in the east that he received in the past.

As protests continue in Ukraine, the focus has already shifted decisively from the Europe-Russia question to a sort of informal referendum on Yanukovych himself. And as the crisis intensifies, it increasingly illustrates how politically risky the middle course that he has tried to steer between Europe and Russia has actually been.

Galvanized By The EU

Nicu Popescu, a senior analyst at the EU Institute for Security Studies in Paris, says, "The front line of Ukrainian public politics seems to be moving into a kind of situation where you have quite a lot of eastern Ukrainians who are disappointed by Yanukovych. So, now the fault line runs not just between east and west, but also within the Yanukovych support groups. Some of them will continue supporting him, and some of them are disappointed by the way he misgoverned Ukraine over the last, almost four years."

The "ultimate driver" in the current crisis is dissatisfaction with Yanukovych, while the issue of the EU Association Agreement is really "a galvanizing factor," Popescu adds. And, historically, the combination of splits within ruling elites and a galvanized political opposition has sometimes produced significant political shifts.

To be sure, the protests have been strongest in the western part of the country, which has always been opposed to Yanukovych. While hundreds of thousands were gathering in Kyiv, the situation in the eastern reaches of the country has been calmer.

In Donetsk, Yanukovych's political base and the epicenter of Ukraine's pro-Russian industrial core, only about 300 pro-EU protesters took to the streets over the weekend and endorsed opposition calls for the president to resign.

In Crimea, a region with strong ties to Moscow that hosts the base of Russia's Black Sea Fleet in Sevastopol, a few dozen pro-Yanukovych demonstrators came out over the weekend waving Russian and Belarusian flags and chanting the slogan, "Forever with Russia."

A deputy in the Sevastopol city council from Yanukovych's Party of Regions even initiated a petition to ask Russian President Vladimir Putin to send Russian military forces to Ukraine to restore order and protect the country from "Western secret services and their agents."

Support for the opposition's call for a general strike has been weak or absent in the traditionally pro-Russian regions.

At the same time, however, open support for Yanukovych has been muted compared to the past. A pro-Yanukovych rally scheduled for December 2 in the president's hometown of Donetsk was abruptly cancelled due to poor turnout.

Since his election in 2010, Yanukovych has tried to steer a middle course between Russia and the EU, a policy that now seems to have pleased neither side and left him vulnerable.

In 2010, he cut a surprise deal with Moscow to allow Russia's Black Sea Fleet to remain at its base in the Crimean port of Sevastopol until at least 2042, but Moscow failed to respond with the expected concessions on natural-gas prices.

In October in Donetsk, Communists rallied in support of Ukraine joining Russia's Customs Union.

At the same time, he pursued negotiations with the EU and pushed parliamentarians from his Party of Regions to pass significant reforms to improve transparency and the rule of law. Since the government announced its about-face on the Association Agreement, at least five deputies have left the Party of Regions faction in the Verkhovna Rada. Deputy Inna Bohoslovska, a formerly staunch Yanukovych supporter from the eastern city of Kharkiv, has called for his resignation.

Perhaps more importantly than soft public support, Yanukovych seems also to be losing the backing of many of the oligarchs who rallied to him in 2010.

Kataryna Wolczuk, who teaches politics and international studies at the University of Birmingham, says that the "oligarchs are crucial."

"They really rallied behind Yanukovych [in the past] and if he loses the support of the oligarchs, Yanukovych will have to go... There have been some fractures within the Party of Regions, but I haven't seen [them on] the scale which is needed," Wolczuk said.

Analyst Popescu says Ukraine's oligarchs are ambivalent about whether they'd prefer risking being swallowed up by their Russian counterparts in the event of closer ties with the Moscow-led Customs Union or whether they'd be willing to take a chance with the reforms and transparency necessary for closer relations with the European Union.

However, many of them are unhappy with the way Yanukovych has mismanaged the balance among the oligarchs and has insinuated himself and his family among them.

"I don't think any of the oligarchs would actually be a huge beneficiary if Ukraine relatively quickly became a state governed by the rule of law. But at the same time they are not very pleased with the way Yanukovych played his hand. He overreached," Popescu said.

"He was not careful enough in maintaining a balance among various oligarchic players. And he himself became basically one of the biggest oligarchs by promoting his family as a key hub of business activity in Ukraine, very often at the expense of oligarchs who were part and parcel of his Party of Regions."

Oligarch-Controlled Media

Some signs of shifting political winds are that oligarch-controlled Ukrainian media seemed to shift the tone of their coverage after the violent clashes between police and protesters in Kyiv on the night of November 29-30.

The Inter television network, owned by billionaire Dmytro Firtash and Yanukovych's chief of staff, Serhiy Levochkin, began showing live reports from the protests and excerpts of speeches by opposition leaders after the Kyiv violence.

Following a police crackdown on protesters over the weekend, Levochkin tendered his resignation -- but Yanukovych says he has refused to accept it.

Media outlets controlled by oligarch and former Yanukovych backer Rinat Akhmetov and by fellow oligarch Ihor Kolomoyskyi also seemed to change their tone.

Wolczuk says the oligarchs are united in their desire to avoid violence.

"The issue is to what extent [the oligarchs] believe Yanukovych can continue to deliver what they need. And it very much, in my view, depends on the popular protests and the perception of the Ukrainians being frustrated and determined to remove Yanukovych from power," Wolczuk said.

"I think that would be probably the tipping point for the oligarchs because they do not want any confrontation and bloodshed."

Speaking to journalists on December 2, Volodymyr Prystyuk of the eastern region of Lugansk, accused the oligarch-controlled media of exaggerating anti-Yanukovych discontent in his region.

"[The media] show close-up shots, make it seem as if some thousands of people have come out, practically all of Lugansk is on the street and all of them are proclaiming demands about resignation [of the president]," Prystyuk said.

"But that isn't happening. And I call to other regions of eastern Ukraine and the picture is the same. I call to Donetsk, Dniepropetrovsk, Zaporozhie, Kharkiv, and the picture is the same. What does this mean? And we know who organized the story with the last so-called Orange Revolution. We know how this is all manipulated. And we know that now there will be attempts to bring money into this region to increase the number of people protesting."

Of course, Yanukovych is a political survivor and it is unclear what kind of support Moscow might give him to help him through the current crisis and, if he weathers that, the 2015 presidential election. Ukraine's pro-Western opposition, although currently galvanized, is notoriously prone to fragmentation.